I have a bit of bladder stone info for you, and will be doing some near-future posts. Dr. Carl Osborne says in part that he does not consider uroliths to be unusual in ferrets and >The Minnesota Urolith Center has received in excess of 100 urinary >stones from ferrets. The most common type is sterile struvite (75%). >Other types include calcium oxalate (12%), and cystine (4%). and Doctor Michelle Hawkins of UC Davis reports that in the last year the numbers of cystine stones and cystine crystals which they have seen have suddenly greatly increased in their lab. (I just got permission to share this with you; it's brand new info.) Cystine stones in many mammals are inclined to involve a genetic kidney factor and to also involve input from diet, esp. ones high in the COLA grouping of amino acids (protein building blocks). As one of our FHL members mentioned in the past, some write-ups also talk about some possible drug causes known in humans. So, the question becomes why there is an increase seen now. Better medical care? More breeding of some lines that have a vulnerability? Higher protein diets showing a vulnerability in some ferrets which doesn't show up with the older foods? Etc. Exactly what is happening with ferrets is still unknown so right now it's a matter of best-guess scenarios. There is a treatment protocol for these in the post of a member who had a past ferret with successful management after past repeated cystine stones. (We had our first ferrets -- 2 of them -- with uroltihs this year after having never encountered them in 23 years with ferrets and had to suddenly begin to learn about this topic.) Uroliths vary with which urinary pH is best and in cause. For more on the topic, see past posts in http://fhl.sonic-weasel.org Our current mode here -- since the stones were removed -- is that the ferrets are back on the standard lower-than-the-latest protein foods (like MF, Ferret Store Supreme, Totally Ferret, 8 in 1 Ultimate, PV, etc.) and they are having regular urine pH checks here and regular exams and testing/imaging. We may in the future have to try to shift to an even lower protein diet or try to meds, or both. The meds involved can sometimes involve some very serious side effects so the general wisdom has so far been to see if the problem recurs before jumping to that. [Posted in FML issue 4624]